Improvement in slide-valves for steam-engines



. To all whom it may concern:

Nrra STATES Armer FFICE- I.

JOHN S. BARDEN, OF PROVIDENCE, RHODE ISLAND, ASSIGNOR TO UNION STEAM VALVE COMPANY, OF MASSACHUSETTS.

IMPROVEMENT IN SLIDE-VALVES FOR STEAM-ENGINES.

Specification forming part of Letters Patent No. 77,569, dated May 5, 1868.

Be it known that I, JOHN S. BARDEN, of Providence, in the county of Providence and State of Rhode Island, have invented a new and useful Improvement in Balance Slide- Valves, of which the following is a full, clear, and exact description, reference being had to the accompanyingdrawings, making a part of this specification, in which- Figure l represents a vertical longitudinal section of a steain-cylinder,balance slide-valve, andsteam-chestembodyingmyinvention. Fig. 2 is a vertical transverse section of the same. Fig. 3 is a sectional plan with the top and steam-inlet removed. Fig. et is a sectional plan with the top and diaphragm removed.

Similarletters ofreferenceindicatelike parts in the several ligures.

The object of my invention is to so construct and arrange a balance slide-valve, cylinder, and steam-chest that the steam will pass into and out of the cylinder without any more waste steam in the passage from the valve-ports to the cylinder than in a cylinder and slide-valve ofthe ordinary construction, and also that the steam will not be obstructed in its passage by having to turn any more angles than in the ordinary slide-valves. A further object is to enable the peculiar construction ot' the valve and steam-chest to be applied to any cylinder having the ordinary slide-valve; and the in vention consists in arranging the balance slidevalve, which is formed with a suitable taper, so that its lower face will be at right angles, or nearly so, with a line drawn through its center to the axial line ofthe cylinder, and having a suitable bearing for the smaller edge of the valve, the seat for the upper face of the valve having ports corresponding with those of the seat for the lower face.

The invention also consists in the construction of the upper ports in a false top or diaphragm of a suficient depth only to contain a thin lm of steam, which shall equalize the pressure exerted upon the two ports, which film of steam is conducted by suitable passages and apertures to the passages below the lower ports, so as to cause an even balance throughout all the varying pressures in the cylinder.

Referring to the drawings, A represents the cylinder of a steam-engine; a a, the steam-passages; b b', the steam-ports, and c the exhaustport.

B is the slide-valve, of the form of a frustum of a hollow wedge, as shown in section in Fig. 2, and is provided with a sleeve for rcceiving a valve-stem. The lower f'ace of the vvalve is at right angles, or nearly so, with a line drawn from its center to the axial line ot' the cylinder.

C represents the steam-chest with the induction-pipe D, and having a diaphragm, E, which forms a part of the steam-chest. This diaphragm is so arranged that its lower face forms the seat for the upper face of the valve B, and at each end of the said diaphragm are spaces g g, to allow of the passage of the steam down by the side of the valve to the ports b b.

F F are two perforated ribs for the purpose of stii'ening the diaphragm. On the under face of the diaphragm E are recesses e', corresponding with the ports in the valve-seat ot' the cylinder. These recesses are ot' a sufficient depth only to contain a thin film of steam, and communicate by means of small openings e e and passages f f with the steam-passages Opposite the smaller end of the steam-valve B is a groove or recess, t', extending the whole length ofthe steam-chest, into which groove the steam enters and presses against the smaller end of the valve, and serves to couilteract in part the pressureof the steam against the larger or forward end of the valve. The faces ot' the larger and smaller ends, h 7c, of the valve B are designed generally to be at right angles with a line drawn through the center of the valve, instead of being at right angles with the lower face, as shown inthe drawings.

The operationis as follows: Steam,bein g admitted through the apertureD into the steamchestC, passes through the spaces g g, around the diaphragm E, down against the sides ot' the valve B,thence through the portband passage aiuto thecylinder. Steam also passes through the passage f and aperture c into the recess in the lower face of the diaphragm E during one motion of the valveB. On the return motion ofthe valve, and when the faces of the same cover the ports b b', the pressure of the steam in the cylinder will act against the two faces of the valve opposite the one port, b, while the exhaust will act in thel same manner against the two faces opposite the other port, b', thus equalizn g the pressure on the upper and lower faces of the Valve. The steam at the same time, having access to the outside of the valve, presses against the two sides l l and the ends h and r, acting at the larger end, 7c, with an.

excess of pressure over that exerted at the smaller end, h, corresponding to the difference in the extent ot' surface at theseends, thus acting to keep the valve forcibly pressed against the two seats, and thus forming a balancevalve.

The above-described valve and steam chamber may be readily adapted to the cylinders of engines already constructed, and may be substituted for those in general use, and thus the advantages of a balance slide-valve can be easily obtained and without great expense.

In case it should be desirable to have the steam enter the side of the steam-chest, the diaphragm may be dispensed with.

The very great amount of pressure exerted upon the inner part of the steam-chest renders it necessary that great care should be taken to solconstruct it bysuitable ribs or otherwise as to prevent any possibility of springing, as in such an event the valves would be inoperative by reason ofthe escape of the steam.

It' the steam-chest is not east with the cylinder, it must be firmly bolted tothe same, and the valve is then to be tittedin after the steamchest is bolted on in such a manner as to be perfectly steam-tight. To insure this, the top part is not to be removed 5 but a suitable opening is provided at the side opposite the wider end of the valve, so that the latter can be properly titted, adjusted, and regulated.

The tiange at the top and sides to which the cover ot' the opening is attached is to be made very stout to further aid in strengthening the steam-chest. Great care must be taken in tting the valve so that the bearing-surface will come in perfect contact with the corresponding surfaces of the steam chest and cylinder. A suicient taper must be given to the valve to cause it to rise and relieve itself whenever a greater pressure occurs in the cylinder than in the steam-chest, which is liable to take place in case the cocks are not opened to lot the water out at the proper time.

What I claim as my invention, and desire to secure by Letters Patent, is-

l. The arrangement of the valve B, con structed as described in respect to the three bearingsurfaees, as and for the purpose set forth.

2. The passages f, so arranged as to connect and communicate between the recesses c and the passages a et, as and for the purpose described.

In testimony whereof I have signed my name to this sdecilication in the presence of two subseribin g witnesses.

JOHN s. BARDEN.

Witnesses:

J AMEs A. WOODBURY, J. H. ADAMS. 

